On Oct 12, 1:49*am, Don Foreman wrote:

Also in my experience smart chargers are not so smart...I have seen
them not charge batteries or overcharge them....always watch them.

Good chargers are the key to battery longevity. They are not cheap,
but they're very good value in the long run. *Overcharging is death on
lead-acid batteries.

I use a simpler version of Spaco's method, minus the spreadsheet. On
the first weekend of each (or every other, I sometimes forget) month I
top up rechargeable batteries in flashlights, remotes, clocks, drills,
jump starters and unused vehicles. For lead-acids I have one 2A/10A
smart charger, one import trickle charger and otherwise homebrews and
lab supplies that don't shut off automatically, but since I'm working
the rounds they won't be forgotten and left on to damage the battery.
The raised hood is a good reminder.

The homebrews can put out enough voltage to equalize the cells of an
old battery and considerably extend its useful life. They have analog
current meters to help set the output current, and I use the $4 HF
DVMs to watch the voltage.

www.batteryfaq.org has a chart of the open circuit voltage reading vs
state of charge over temperature. A battery that won't charge to 100%
is getting old or needs attention.

jsw